Glasgow girl...our neuro told my husband to find his own timings.
If the drugs wear off after 3 hours, take the next dose about 10 mins before the 3 hours is up.
When you get the timing right and experience no symptoms, try to lower the dose a bit until the symptoms are showing again.
My husband takes his Sinemet every 2 hours and doesn't have off times.
You could discuss the situation with your Parkinsons nurse but the rigid timing regime doesn't work for lots of patients who are often able to find a way that works for each individual.